In the long term evolution (LTE) system, diversity methods for the cases that there are two transmission antennae and that there are four antennae are defined in the downlink, wherein, the diversity method for the case that there are two transmission antennae is space-frequency block coder (SFBC), whose coder matrix is shown in equation (1):
                                              ⁢                              Antenna            ⁢                                                  ⁢            1            ⁢                                                  ⁢            Antenna            ⁢                                                  ⁢            2                    ⁢                                          ⁢                                                                                          Frequency                    1                                                                                                                    Frequency                    2                                                                        ⁡                          [                                                                                          S                      1                                                                                                  -                                              S                        2                        *                                                                                                                                                        S                      2                                                                                                  S                      1                      *                                                                                  ]                                                          (        1        )            
In equation (1), each column indicates one transmission antenna and each row indicates one transmission frequency; S1 indicates the symbol sent in the first time, S2 is the symbol sent in the second time, S1* and S2* indicate the conjugates of S1 and S2 respectively.
The diversity method for the case that there are four transmission antennae is space-frequency block coder (SFBC)+frequency switch transmit diversity (FSTD), whose coder matrix is shown in equation (2):
                                              ⁢                              Antenna            ⁢                                                  ⁢            1            ⁢                                                  ⁢            Antenna            ⁢                                                  ⁢            2            ⁢                                                  ⁢            Antenna            ⁢                                                  ⁢            3            ⁢                                                  ⁢            Antenna            ⁢                                                  ⁢            4                    ⁢                                          ⁢                                                                                                                                                                                                                                                            Frequency                                1                                                                                                                                                                                                        Frequency                                2                                                                                                                                                                                                                                                  Frequency                          3                                                                                                                                                                                      Frequency                    4                                                                        ⁡                          [                                                                                          S                      1                                                                            0                                                                              -                                              S                        2                        *                                                                                                  0                                                                                                              S                      2                                                                            0                                                                              S                      1                      *                                                                            0                                                                                        0                                                                              S                      3                                                                            0                                                                              -                                              S                        4                        *                                                                                                                                  0                                                                              S                      4                                                                            0                                                                              S                      3                      *                                                                                  ]                                      ⁢                                                      (        2        )            
In equation (2), each column indicates one transmission antenna and each row indicates one transmission frequency; S1, S2, S3 and S4 indicate the symbols sent at the first, second, third and fourth time points respectively, S1*, S2*, S3*, and S4* indicate the conjugates of S1, S2, S3 and S4 respectively.
With the continuous development of the LTE system, in order to increase the data transmission rate and spectrum efficiency in the downlink in the LTE-Advanced system, the related standards specify that at most eight transmission antennae can be used. In the present LTE standards, however, the diversity method for the eight transmission antennae is not defined, thus the data transmission based on eight transmission antennae cannot be implemented in the LTE-Advanced system so far, which brings inconvenience to the practical applications.